Zoom lens apparatus

ABSTRACT

A zoom lens apparatus comprising an actuating ring adapted to be rotated integrally with a zooming ring, and a first, a second and a third lens group which are caused to move in the direction of the optical axis independently of each other as said actuating ring is rotated, and being operative so that the focal distance may be progressively altered continuously without causing any aberration and/or marginal blurring throughout the range from the extreme wide angle to the telephoto position by the mere rotation of said single actuating ring.

United States Patent 1 Nagashima Aug. 14, 1973 54] ZOOM LENS APPARATUS3,090,282 5/1963 Angenieux 350/255 [75] lnventor: Motoi Naguhima, Tokyo,Japan Primary Examiner David schonberg [73] Assignee: Shims KogakuKabuahiltl Kaisha, Assistant Examiner-Michael J. Tokar Tokyo, JapanAtt0meyCushman, Darby & Cushman [22] Filed: Feb. 18, 1972 ABSTRACT [2U P2278530 A zoom lens apparatus comprising an actuating ring adapted to berotated integrally with a zooming ring, 52 us. c1 350/255, 350/184,350/187 and a first a Second and a third lens group which are 51 Int.Cl. G02b 7/02 caused to move in the direction of the Optical axis inde-[58] Field of Search 350/184, 186, 187, Pendemly of each other as saidwmatihs g is 350/255 tated, and being operative so that the focaldistance may be progressively altered continuously without [56]References Cited causing any aberration and/or marginal blurring UNITEDSTATES PATENTS throughout the range from the extreme wide angle to 3 455628 7/1969 B k 350/187 the telephoto position by the mere rotation ofsaid sinac 3,663,093 5/1972 Iida gle actuatmg 2,902,901 9/1959 Back350/255 5 Claims, 3 Drawing Figures PAIENIEDAun 14 ms SHEET 2 [IF 3 N QIPATENTEUwsmszs 3.752 565 sum 3 0F 3 FIG. 3

ZOOM LENS APPARATUS BACKGROUND OF THE INVENTION 1. Field of theInvention The present invention is concerned with a zoom lens apparatusfor use in a photographic camera, and more particularly, it pertains toa zooming mechanism which is capable of causing a plurality of groups oflens elements to move forwardly and backwardly for a required amountrespectively by the mere rotation of a single actuating ring.

2. Description of the Prior Art:

A lens system which is used in a photographic camera, in general, iscomprised of a plural number of groups of lens elements. It is usualthat the complexity of this lens arrangement increases for articles ofhigher grades. In particular, in a zoom lens which is designed so that asingle train of lenses is usable for a focus ranging from the extremewide angle to the exreme telephoto position, not only the lens systembecomes markedly complicated but also there arises the necessity thatthe respective groups of lens elements have to be moved forwardly andbackwardly respectively. Hence, conventional zoom lenses had thedrawback that their overall size tended to become bulky with theaccompaniment of an increase in their weight and that, accordingly, theywere inconvenient to carry. Furthermore, conventional zoom lenses werearranged so that two groups of lens elements were caused to move by azooming operation, with the result that their zooming range wasinevitably narrow and that many of them had the troubles of developingaberration and margin blurring.

SUMMARY OF THE INVENTION It is, therefore, a primary object of thepresent invention to provide a zoom lens apparatus arranged so thatthree groups of lens elements are caused to move forwardly andbackwardly in the direction of the optical axis for required amountsrespectively, as a single ring is rotated, and operative so that thesynthesized focal distance of the respective lens elements can bealtered arbitrarily in the range from the extreme wide angle to theextreme telephoto position.

Another object of the present invention is to provide a zoom lensapparatus arranged so that, whenever it is carried, it can have anextremely reduced length.

Still another object of the present invention is to provide a highlyefficient zoom lens apparatus which gives rise to no problems such asaberration and marginal blurring throughout the range from the extremewide angle to the extreme telephoto position.

Other objects as well as the attendant advantages of the presentinvention will become apparent from the following detailed descriptionof the preferred embodiments when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation of the zoomlens apparatus of the present invention, the upper half of which is insection;

FIG. 2 is a plan view of only the main parts of FIG. 1 in an seriallyexploded fashion and arranged in the optical axis; and

FIG. 3 is a side elevation similar to FIG. 1, showing another example ofthe zoom lens apparatus of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIGS. 1 and 2, referencenumeral 1 represents a known lens mount which can be detachably attachedto a camera body not shown. Numeral 2 represents a ring carrying focaldepth-indicating graduations and having fixed indices 2a as well asfocal depth-indicating graduations 2b formed on the circumferentialsurface thereof, and also having slots 2c and 211 formed therethrough inthe circumferential direction, and being secured to the lens mount 1 bya screw 3. Numeral 4 represents a guide ring having on the innercircumferential surface a groove 4a which extends in the optical axisand a narrow-pitched threaded portion 412, and being secured by a screw5 to the ring 2. Numeral 6 represents an actuating ring having, locallyin the circumferential wall, a slot 6a inclined relative to the opticalaxis and being mounted between the ring 2 and the guide ring 4. Numeral7 represents a zooming ring rotatably mounted on the external side ofthe ring 2 which carries focal depth-indicating graduations andprovided, on its external circumferential surface, with synthesizedfocal distance-indication graduations 7a for the lens system which, inturn, cooperate with the fixed indices 2a and also coupled integrally tothe actuating ring 6 by a pin 8 which is passed through the slot 20.Numeral 9 represents a first helicoid ring having, on its externalcircumferential surface, a threaded portion 9a meshing with the threadedportion 4b and also having, on its inner circumference, a helical thread9b and being coupled integrally to the actuating ring 6 by a screw10.-Numeral 11 represents a second helicoid ring having, on its outercircumference, a helical thread Ila meshing with the helical thread 912,a slot 1 lb extending in the direction of the optical axis, and anarrowpitched threaded portion 11c. Numeral 12 represents a lens holdermounted within the second helicoid ring 11 to hold a first group L, oflens elements containing a known diaphragm means 13. Numeral 14represents a coupling strip having one end portion received in thegroove 4a and the other end portion coupled integrally to both of thesecond helicoid ring 11 and the lens holder 12 by a screw 15. Numeral 16represents a diaphragm adjusting ring rotatably mounted onto the outerside of the lens mount 1 and having, on its outer circumference,diaphragm graduations 16a which cooperate with the fixed indices 20 andbeing assigned to operate the diaphragm means 13. Numeral l7 representsa lens holder for holding a second group L oflens elements, and beingslidably received via a metal ball 17a within the second helicoid ring11. Numeral 18 represents a pin passing through the slots 6a and 11b andbeing secured to the lens holder 17. Numeral 19 represents a fourthhelicoid ring slidably mounted on the inside of the actuating ring 6 andhaving, in its cir cumferential wall, a slot 19a which is inclinedrelative to the optical axis and also having, on the inside of itsforward end, a helicoid ring 1 provided, on its outer circumference,with a threaded portion 21a which meshes with the threaded portion andalso provided with a helical thread 211: formed on its innercircumference and secured by a screw 22 to the fourth helicoid ring 19.Numeral 23 represents a third helicoid ring having,

on its outer circumference, a helical thread 2311 which meshes with thehelical thread 2llb and also having a helical thread 23b formed on itsinner circumference and further having a slot 23c having one open endand extending in the direction of the optical axis. Numeral 24represents a pin secured to the second helicoid ring 11 and having itsforward end portion received in the aforesaid slot 23c of the thirdhelicoid ring 23. Numeral 25 represents a lens holder having, locally onits outer circumference, a helical thread 25a which meshes with thehelical thread 2312, and being assigned to hold a third group L of lenselements. Numeral 26 represents a focusing ring mounted on the outerside of the ring 2 and coupled integrally by a screw 27 to the lensholder 25 and provided, locally on its external circumference, withdistance graduations 26a which cooperate with the central index 2 b' ofthe focal depthindicationg graduations 2b.

Description will hereunder be made on the actions of the aforesaidapparatus. It should be understood that the description of these actionsis based on the assump' tion that the directions of the respectivethreaded portions and of the helical threads are both selected in such away that, when the zooming ring 7 is rotated clockwise as viewed fromthe right side of the drawing, both the second helicoid ring 11 and thelens holder 25 are caused to move towards the left side at theirpositions shown in FIG. 1. By rotating the zooming ring 7 clockwise inits position of FIG. 1, the actuating ring 6 will rotate also in thesame direction. In this part of operation, the first helicoid ring 9rotates clockwise also. However, the second helicoid ring 11 isinhibited of its rotation because the coupling strip 14 is received inthe groove 4a which is formed in the guide ring 4. Accordingly, thesecond helicoid ring 11 is caused to move towards the left side as thefirst helicoid ring 9 is rotated. As a consequence, the first group L oflens elements is causedto move towards the left side along the opticalaxis. On the other hand, due to the aforsaid rotation of the actuatingring 6, the lens holder 17 is caused to move, via the pin 18 whosemovement is limited by the slot 6a which is inclined relative to theoptical axis, towards the right side relative to the second helicoidring 11, whereas the second group L of lens elements is caused to movetowards the right side relative to the first group L, of lens elements.Furthermore, by the aforesaid rotation of the actuating ring 6, both thepin 20 and the fourth helicoid ring 19 are rotated also in the aforesaiddirection. In this part of operation, however, it should be understoodthat the direction of inclination and the degree of angle of inclinationof the slot 19a formed in the fourth helicoid ring 19 are both selectedin such a way that they are in agreement with the orientation and thepitch of the thread of the threaded portion 21a of the helicoid ring 21.In addition, the pin 24 which is secured to the second helicoid ring 11is received in the slot 230 formed in the direction of the optical axisin the third helicoid ring 23. Therefore, due to the rotary movements ofboth the fourth helicoid ring 19 and the helicoid ring 21 resulting fromthe rotation of the actuating ring 6, the third helicoid ring 23together with the lens holder 25 is caused to move towards the left sidealong the optical axis. As a consequence, the third group L of lenselements is caused to make a movement towards the left side along the optical axis relative to the first group L of lens elements. Thus, thesynthesized focal distance of the lens system which is constituted bythe first, second and third groups L L and L, of lens elements isprolonged and will provide a lens arrangement having a longer focaldistance than that of the lens arrangement in the state shown in FIG. 1.

As will be clear from the foregoing statement, if there is made atheoretical calculation of the changes occurring in the synthesizedfocal distance due to the relative movements of the respective groups LL and L of lens elements based on such factors as the focal distancesand the radii of curvature of those lens elements which constitute thefirst, second and third groups L L and L; of lens elements,respectively, and if the pitches and the orientations of the threads ofthose helical threads such as 9b, 11a, 21b and 23a as well as suchfactors as the directions of inclination and the degrees of angle ofinclination of the slots 6a and 19a are selected appropriately so thatthey are in agreement with the result of said calculation, then it ispossible to obtain, for example, a photographic zoom lens whose focaldistance can be altered in the range from the extreme wide angle to theextreme telephoto position by a same single train of lens elements. Itshould be understood also that, according to the apparatus of thepresent invention, by rotating the focusing ring 26, the lens holder 25alone is caused to move forwardly and backwardly relative to the thirdhelicoid ring 23 in the direction of the optical axis. By virtue of thisaction of the lens holder 25, it is possible to perform adjustment ofthe focus on the film face. Also, it is possible to make any arbitraryadjustment of the size of lens diaphragm to obtain a required opening byrotating the diaphragm adjusting ring 16.

FIG. 3 shows another example having an arrangement somewhat differentfrom that described above. Since, however, this second example issimilar in its basic structure to the first one, those parts and siteswhich are similar to the ones shown in FIG. 1 are indicated by likereference numerals, and parts and sites having the same functions asexerted by those shown in FIG. I are indicated by like referencenumerals with a prime, and therefore the detailed explanation of thestructure and function of such parts and si es is omitted. It should beunderstood also that, as compared with the arrangement shown in FIG. 1,the example shown in FIG. 3 is given the consideration so that themanufactural processing and the arrangement or combination of therespective parts may be accomplished a little more easily. This instantexample shown in FIG. 3 differs from the one shown in FIG. 1 in thefollowing three points, i.e., that the actuating ring 6 is coupled, viaa screw 8 threadably attached to the zooming ring 7, to the latter 7;that the fourth helicoid ring 19 is coupled integrally to the actuatingring, and the pin 20 which is received in the inclined slot 19a formedin said fourth helicoid ring 19' is secured to the second helicoid ring11; and further that the lens holder 25 is secured to an auxiliary ring25' which is coupled to the focusing ring 26. Also, in this secondexample, there are given the following considerations that a pin 18 isreceived, via a roller 18a rotatably mounted on this pin 18, in the slot6a which is formed in the actuating ring 6, and also that the pin 20' isreceived, via a roller 20a rotatably mounted thereon, in the slot 19awhich is formed in the fourth helicoid ring 19', so that the slidingmovements of these pins in their mating slots can be performed smoothly.

I claim:

1. A zoom lens apparatus comprising: a mount member; a diaphragmadjusting ring rotatably mounted on said mount member; a ring carryingfocal depthindicating graduations and being secured to said mountmember; a focusing ring rotatably mounted on said ring carrying focaldepth-indicating graduations; a zooming ring rotatably mounted on theoutside of said ring carrying focal depth-indicating graduations; anactuating ring rotatably mounted on the inside of said ring carryingfocal depth-indicating graduations and operatively coupled to saidzooming ring and provided in its forward end with a first slot inclinedrelative to the optical axis; a guide ring operatively coupled to saidring carrying focal depth-indicating graduations and provided, in itsinner circumferential face, with a groove extending in the direction ofthe optical axis; a first helicoid ring operatively coupled to saidactuating ring and threadably received in said guide ring; a secondhelicoid ring threadably received in said first helicoid ring andprovided, at its forward end, with a second slot extending in thedirection of the optical axis and, at its rearward end, with a couplingstrip engaging in said groove; a first lens holder operatively coupledto said second helicoid ring; a first group of lens elements mounted onsaid first lens holder; a second lens holder slidably received in saidsecond helicoid ring; a second group of lens elements mounted on saidsecond lens holder; a first pin secured to said second lens holder andreceived in said first and second slots; a third lens holder operativelycoupled to said focusing ring; a third group of lens elements mounted onsaid third lens holder; a

third helicoid ring threadably received in said third lens holder andprovided, at its one end, with a third slot extending in the directionof the optical axis; a seond pin secured to said second helicoid ringand received in said third slot; a fourth helicoid ring threadablyreceiving said third helicoid ring and provided, at one end portion,with a fourth slot inclined relative to the optical axis; and a thirdpin received in said second slot and secured to either one of saidactuating ring and said second helicoid ring; whereby the apparatus isoperative so that, as said zooming ring is rotated, said first, secondand third groups of lens elements are caused to move forwardly andbackwardly in the direction of the optical axis for required amounts,respectively,

2. A zoom lens apparatus according to claim 1, in which said first groupof lens elements contains a diaphragm means operated by said diaphragmadjusting ring.

3. A zoom lens apparatus according to claim 1, in which said first groupof lens elements is comprised of two lens elements, said second group oflens elements is comprised of two lens elements, and said third group oflens elements is comprised of one lens element.

4. A zoom lens apparatus according to claim 1, in which said second lensholder is received in said second helicoid ring via a metal ball carriedby said second lens holder.

5. A zoom lens apparatus according to claim 1, said first and third pinsare received in said first and fourth slots, respectively, via rollersrotatably mounted on these pins, one for each pin.

1. A zoom lens apparatus comprising: a mount member; a diaphragmadjusting ring rotatably mounted on said mount member; a ring carryingfocal depth-indicating graduations and being secured to said mountmember; a focusing ring rotatably mounted on said ring carrying focaldepth-indicating graduations; a zooming ring rotatably mounted on theoutside of said ring carrying focal depth-indicating graduations; anactuating ring rotatably mounted on the inside of said ring carryingfocal depth-indicating graduations and operatively coupled to saidzooming ring and provided in its forward end with a first slot inclinedrelative to the optical axis; a guide ring operatively coupled to saidring carrying focal depth-indicating graduations and proVided, in itsinner circumferential face, with a groove extending in the direction ofthe optical axis; a first helicoid ring operatively coupled to saidactuating ring and threadably received in said guide ring; a secondhelicoid ring threadably received in said first helicoid ring andprovided, at its forward end, with a second slot extending in thedirection of the optical axis and, at its rearward end, with a couplingstrip engaging in said groove; a first lens holder operatively coupledto said second helicoid ring; a first group of lens elements mounted onsaid first lens holder; a second lens holder slidably received in saidsecond helicoid ring; a second group of lens elements mounted on saidsecond lens holder; a first pin secured to said second lens holder andreceived in said first and second slots; a third lens holder operativelycoupled to said focusing ring; a third group of lens elements mounted onsaid third lens holder; a third helicoid ring threadably received insaid third lens holder and provided, at its one end, with a third slotextending in the direction of the optical axis; a seond pin secured tosaid second helicoid ring and received in said third slot; a fourthhelicoid ring threadably receiving said third helicoid ring andprovided, at one end portion, with a fourth slot inclined relative tothe optical axis; and a third pin received in said second slot andsecured to either one of said actuating ring and said second helicoidring; whereby the apparatus is operative so that, as said zooming ringis rotated, said first, second and third groups of lens elements arecaused to move forwardly and backwardly in the direction of the opticalaxis for required amounts, respectively.
 2. A zoom lens apparatusaccording to claim 1, in which said first group of lens elementscontains a diaphragm means operated by said diaphragm adjusting ring. 3.A zoom lens apparatus according to claim 1, in which said first group oflens elements is comprised of two lens elements, said second group oflens elements is comprised of two lens elements, and said third group oflens elements is comprised of one lens element.
 4. A zoom lens apparatusaccording to claim 1, in which said second lens holder is received insaid second helicoid ring via a metal ball carried by said second lensholder.
 5. A zoom lens apparatus according to claim 1, said first andthird pins are received in said first and fourth slots, respectively,via rollers rotatably mounted on these pins, one for each pin.